Waveguides are an indispensable technology that is widely used in different technology fields, such as wireless and wire-line communications, metrology, as well as, sensing and security. In particular, dielectric waveguides have been used in transmission line applications, as well as in waveguide circuits to confine, process and transmit light over various distances. For example, dielectric waveguides are used to transmit light over thousands of kilometers (km) in long-distance fiber-optic transmission. In another application, dielectric waveguides are used in integrated photonics for light processing and transmission over tens or hundreds of micrometers (μm).
Dielectric waveguides formed of different size, shape, and materials are required for different applications. For sub-millimeter/Terahertz frequency applications of guided-waves, waveguide circuits with small dimension are desired in order to satisfy the associated single-mode and modal-operation conditions. However, the fabrication of small dimension waveguides, especially those made with metallic material, is particularly challenging. Moreover, metallic waveguides for sub-millimeter/terahertz frequency applications are relatively inflexible and costly to manufacture.